1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly, to a semiconductor device having an anti-reflective cap and a spacer, a method of manufacturing the same, and a method of manufacturing a photoresist pattern using the same.
2. Description of the Related Art
A highly integrated semiconductor device is formed using highly reflective materials such as polycrystalline silicon, aluminum, or metal silicide. When a photoresist film is formed on the highly reflective material layers, incident light is reflected from the highly reflective material onto the photoresist film during an exposure process to form a photoresist pattern. As a result, a deformed photoresist pattern is obtained.
Such a problem becomes more serious in the exposure process in which an exposure source emitting a short wavelength of 248 nm or less is used for forming a pattern according to a sub-micron design rule. In particular, when a pattern having a large step difference is formed of a reflective material, the density of the light reflected from the edge of a reflective material pattern increases more, and the deformation of the photoresist pattern is also increased.
In order to solve such a problem, there is a method of forming an anti-reflective film under or on the photoresist film before performing a photolithography process. In the method, the anti-reflective film must be formed whenever the photolithography process is performed and removed after the patterning is completed. Therefore, the process of manufacturing the semiconductor device becomes more complicated.
To solve the above problems, it is an objective of the present invention to provide a semiconductor device of a new structure by which it is possible to effectively prevent light from being reflected from a reflective pattern.
It is another objective of the present invention to provide a method suitable for manufacturing the semiconductor device of the new structure.
It is still another objective of the present invention to provide a method of manufacturing a fine photoresist pattern more simply by effectively preventing light from being reflected from a reflective pattern using the semiconductor device.
To achieve the first objective, there is provided a semiconductor device, comprising an anti-reflective cap formed on an upper surface of the reflective pattern formed on a semiconductor substrate and an anti-reflective spacer formed on side walls of the reflective pattern formed on the semiconductor substrate.
The anti-reflective cap preferably functions as an interference anti-reflective film which causes the light reflected from the surface of the reflective pattern to destructively interfere with the light reflected from the surface of the anti-reflective cap, thus reducing a reflectance to not more than 20% and is formed of a material having a refractive index of not less than 1.0 under incident light having a wavelength of not more than 365 nm.
The anti-reflective spacer preferably functions as an absorbent anti-reflective film which absorbs the light reflected from the surface of the reflective pattern and the surface of the substrate, thus reducing a reflectance to not more than 20% and is formed of a material having a refractive index of not less than 1.0 and an extinction coefficient of not less than 0.05 under incident light having a wavelength of not more than 365 nm.
In a method of manufacturing a semiconductor device according to the present invention for achieving the second objective, a stacked structure comprised of a reflective pattern and an anti-reflective cap is formed on the semiconductor substrate after providing a semiconductor substrate. Then, an anti-reflective spacer is formed on side walls of the stacked structure.
The formation of the stacked structure proceeds as follows. After forming a reflective material film on the semiconductor substrate, an anti-reflective film is formed on the reflective material film. Then, after forming a photoresist film on the anti-reflective film, a photoresist pattern is formed by exposing and developing the photoresist film. Finally, a stacked structure comprised of the anti-reflective cap and the reflective pattern is completed by etching the anti-reflective film and the reflective material film using the photoresist pattern as an etching mask.
The anti-reflective spacer is formed by forming an anti-reflective film on the entire surface of the resultant structure on which the stacked structure is formed and anisotropically etching the anti-reflective film.
In a method of manufacturing a photoresist pattern for achieving the third objective, after providing a semiconductor substrate, a stacked structure comprised of a reflective pattern and an anti-reflective cap is formed on the semiconductor substrate. An anti-reflective spacer is formed on the side walls of the stacked structure. A first interlayer dielectric film is formed on the entire surface of the semiconductor substrate on which the anti-reflective spacer is formed. A photoresist film is formed on the first interlayer dielectric film. A photoresist pattern exposing the first interlayer dielectric film area under which the reflective pattern is buried, is formed by exposing and developing the photoresist film.
After forming a contact hole exposing a partner some of the stacked structure and a partner of the anti-reflective film spacer and the semiconductor substrate, the photoresist pattern is removed. The contact hole may be formed by etching the first interlayer dielectric film using the photoresist pattern as an etching mask.
After forming the contact hole, a conductive film pattern filling the contact hole is formed. A second interlayer dielectric film is formed on the entire surface of the resultant structure on which the conductive film pattern is formed. After forming a photoresist film on the second interlayer dielectric film, a photoresist pattern exposing the second interlayer dielectric film area under which the conductive film pattern, the stacked structure, and the anti-reflective film spacer are buried, is formed by exposing and developing the photoresist film.
Preferably, after forming the second interlayer dielectric film, of an anti-reflective film may be formed on the second interlayer dielectric film.
When the photoresist pattern is formed using the semiconductor device having the anti-reflective cap and the spacer according to the present invention, the deformation of the photoresist pattern by the light reflected from the reflective pattern is minimized. Also, it is possible to simplify the process of forming the photoresist pattern.